The present invention is concerned with an apparatus and method of supplying carbon dioxide dissolved in water. More particularly, the invention is concerned with the supply to plants in water, cultivating mediums for cells of animals and plants, potable water, etc., with carbon dioxide dissolved in water.
Systems which should be continuously supplied with a dissolved carbon dioxide in water include those involved with photosynthesis in plants and cultivation of cells of animals. For this purpose, conventionally, a gas source from outside, such as a bomb of carbon dioxide, is used and contacting of the gas with a liquid forms dissolved carbon dioxide therein. In this method, however, the gas-feeding rate can be controlled only by the contacting area of gas and liquid and the partial pressure of the carbon dioxide gas. Moreover, the bombs must constantly be replaced when they become empty. Maintenance is troublesome.
Aquatic plants living with ornamental fish are supplied with carbon dioxide gas by introducing carbon dioxide into a tube having the upper end closed and the lower end opening in the water so that water entering through the open end of the tube is brought into contact with the carbon dioxide gas contained in the tube, thus dissolving carbon dioxide gas in the water. The carbon dioxide gas must be introduced as frequently as about once per day, which is laborious. Furthermore, the carbon dioxide gas continues to be supplied even when there is no light to give rise to photosynthesis. Controlling the supply of carbon dioxide in this way is very difficult.